Collapsible trailer hitch for truck loaders



United States Patent Max .1. Lugash [72] Inventor Los Angeles, California [21] Appl. No. 805,781

March 10, 1969 [45] Patented Dec. 8, 1970 Primary Exuminer- Leo Friaglia Attorney-Fulwider, Patton, Rieber, Lee & Utecht ABSTRACT: A collapsible trailer hitch attachment for truck power loaders of the type in which a load platform is mounted on the swingable rear end of a lifting arm framework that, in turn, is pivotally connected at its forward end to a supporting 214/77 frame, the lifting arm framework at opposite ends pivotally B U mounting a pair of oppositely swingable trailer hitch members 2 /4 which may alternatively be disposed generally within the plane 314/77 of the lifting arm framework or projecting downwardly and rearwardly from the lifting arm framework, the members in lowered condition being coupled together and at the juncture of their coupled ends mounting a ball hitch to receive the ball socket of a trailer tow bar.

[22] Filed [73] Assignee Maxon Industries, Inc.

Los Angeles, California [54] COLLAPSIBLE TRAILER HITCH FOR TRUCK LOADERS 7 Claims, 8 Drawing Figs.

[51] Int. [50] Field of Search.

[56] References Cited UNITED STATES PATENTS 6/1958 Lugash.........................

COLLAISIBLE TRAILER HITCH FOR TRUCK LOADERS BACKGROUND OF THE INVENTION BRIEF DESGRIPTION OF THE DRAWINGS Fig. l is a perspective view of the rear end of a truck mounting a platform loader on which the collapsible trailer hitch attachment of the present invention is mounted, the hitch being shownin operative position.

. FIG. 2 is a side elevational'view of the apparatus shown in FIG. 1.

FIG..3 is apartial plan view,1on an enlarged scale, taken in the direction of the line 3-3 of FIG. 2.

FIG. 4 is a sectional view, on an enlarged scale, taken on the line 4-4 of FIG. 1.

Fig. 5 is a partial plan view taken on the line 5-5 of FIG. 4.

FIG. 6 is a view similar to FIG. 2, but on an enlarged scale,

showing the stowed position of-the collapsible hitch and also showing, in phantom outline,the extended operative position ofthe hitch.

FIG. 7 is a sectional view, on an enlarged scale, taken on the line 7-7 of FIG. 2. i

FIG. 8 is a partial sectional view taken on the line 8-8 of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG.- 1, a truck 10 includes a bed 11 mounting a dock bumper extension 12 at the tailgate position. The chassis 13 of the truck mounts a tailgate loader which may be either of the tailgate-closing-type, in which the platform in operative position closes the tailgate of the truck, or of the invertable-platform type exemplified in my prior U.S.' Pats. No. 2,837,227 and No. 2,989,196. The latter type of loader is depicted in the drawings and includes a pair of supporting brackets 14 affixed to' opposite sides of the truck chassis 13 to depend downwardly therefrom to rigidly support a main frame member 15. This main frame has a spaced pair of lifting link ages connected thereto, each of the linkages comprising a lower arm 16 and an upper arm 17 pivotally connected at forward ends to the main frame 15, as is indicated at axes l8 and 19, respectively. p

The lower arms 16, adjacent their rear ends, are rigidly interconnected by a channel shaped crossmember 20, thereby defining an essentially rigid lifting arm framework that is swingable about the axis of the pivot pins 18. At its rear end, each of the lower arms 16 is received and pivotally mounted between the lower ends of apair of brackets 21, the two pairs of brackets being rigidly interconnected by a crossbar 22. The

upper ends of the two pair of brackets 21 extend upwardly beyond the upper edge of the cross bar 22 for pivotal connection, as indicated at 23, to the rear ends of upper arms 17, the

hinge pins definingthe axis 23 also pivotally supporting a substantially rectangular platform 25 that is invertable over the lifting linkages.

The power means for raising and lowering the lifting linkages may be any of the conventional types but, preferably, comprises an electrohydraulic system, which includes a hydraulic cylinder 27 having its forward end pivotally interconnected at 28 to the main frame member 15. A piston rod 29 protrudes rearwardly from the hydraulic cylinder to be pivotally connected at its rear end to the channel brace 20. Thus, as is shown in FIG. 3, the channel brace 20 at its midpoint and along itsforwardlydisposed wall mounts a generally U-shaped bracket 30 the opposed walls of which seat a pivot pin 31 to pivotally mount a bearing block 32 rigidly affixed to the rear end of the piston rod 29. A power unit, conventionally generally designated by'the numeral 33. Suffice it to say that the power means upon opening of a suitable relief valve permits lowering of the lifting linkages and the apparatus carried thereon by the weight of the-apparatus. For lifting of the linkage systems the electrical motor is energized to drive the pump to effect the introduction of pressure fluid to the rear end of the hydraulic cylinder 2'], driving the piston therein forwardly to effect retraction of the piston rod with consequent elevation of the lifting arms.

Referring to FIGS. 2 and 6, and considering only the power loader elements and the space occupied thereby, it will be apparent that very little clearance is available for the mounting of a trailer bitch in this environment. In the case of the old tailgate loader, in which the load platform also constitutes the tailgate, and, therefore, does-not have to be stowed under the bed of the truck above the linkages, the problem is not as severe. However, the collapsible trailer hitch attachment of my invention is usable with eithertype of loader and, in either event, does not interfere with the normal use of the loader for freight handling purposes and provides a quickly erectable trailer hitch that positions the ball joint or other trailer coupling connection sufficiently far to the rear so as to avoid short coupling such as would inhibit cornering with the trailer attached.

More particularly, in view of the space limitations presented by the loader attached to the truck 10, certain components of the loader are also utilized as components of the trailer hitch attachment. Thus, the essentially rigid framework defined by the lower linkage arms 16 and interconnections thereof at front and rear ends is utilized as apreferred base for mounting the components of the collapsible hitch, although other attachment points of the loader may be utilized. The elements of the hitch are collapsibleto within the plane of this supporting framework, approximately, and upon being erected into operative position, defines a truss with this framework that is well adapted to stand the loads imposed by the trailer to be towed.

More specifically, a ladderlike ball hitchframe 35 is defined by a spaced pair of bars 36 that are rigidly interconnected by a spaced pair of straps 37 and 38. As indicated in FIG. 1, the bars 36 are held spaced apart by the straps 37 and 38 a distance no less than the outside diameter of the hydraulic cylinder 27 and the straps 37 and 38 are disposed along those edges of the bars 36 which face downwardly and forwardly. The upper or rear end of the ladder frame 35 is pivotally connected to the pivot pin 31 that also pivotally interconnects the rear end of the piston rod 29 to the channel brace 20. Thus, as indicated in FIG. 6, when the ladder frame 35 is swung forwardly and upwardly into its stowed position, the piston rod 29 has ample clearance between the ladder frame bars 36 and these bars also receive the rear end portion of the hydraulic cylinder 27 therebetween with clearance. The lower end portions of the ladder frame bars 36 are angularly related to the' Y posite ends rigidly affixed in the confronting surfaces of the pair of lower arms 16. Referring to FIGS. 4 and 5, each channel 42 at its rear end, between its opposite walls, contains onehalf of a bearing block 43 that is held in place by a fastener means 44 that also extends through an opposed pair of straps that'embrace the walls of the channel 42 therebetween. These straps extend forwardly beyond the channel 42 and have a therebetween, as by welding 47, the rod 41 thus pivotally supporting the channel arm. In order to prevent lateral displacement of the A frame 40 relative to its supporting rod 41, the rod adjacent each of its ends is provided with a spaced pair of washers 49 between which the bearing parts 43 and 46 are pivotally confined.

Adjacent the rear end of the A frame 40, and disposed on the upper walls of the two channels 42, the channels are rigidly connected by a crossing'strap 51. At their rear extremity, the channels 42 are rigidly interconnected by a rearwardly facing bar 52 from which a spaced pair of plates 53 and 54 project rearwardly to define a tongue receiving slot. As is shown in FIG. 8, the plates 53 and 54 at their forward ends have a filler piece 55 sandwiched therebetween which, like the forward ends of the plates 53 and 54, is securely attached to the A frame plate 52 by means of welding.

. In order to stow the trailerhitch, one of the A frame chan-' nels 42 is provided with a side'wardly projecting perforated tab 57 that is positioned for registration of the hole therein with the hole of another tab 58 secured to the confronting side of the adjacent one of the lower lifting arm 16. For storing the device, the ladder frame 35 is first fully raised to within the plane of the linkage arms 16, in embracing relationship to the hydraulic cylinder 27, in the manner previously described. The A frame 40 is then raised about its pivot axis defined by the rod 41 to bring the holes on the pair of tabs 57 and 58 into registration. Subsequently, a retainer pin 60 that isconnected to one end of a chain 61 whose other end is secured, via a fastener 62, to any convenient portion of the apparatus, is inserted through the aligned holes to maintain the parts in the stowed position indicated in solid outline in FIG. 6. From this figure it will be observed that both the ladder frame 35 and A frame 40 lie generally or in major part within the plane of the lower arms 16, with the angled portions of the ladder frame 35 and the ball joint support plate or tongue 39 projecting downwardly between the channels 42 of the A frame, with ample road clearance. Further, from an inspection of FIG. 6, it will be observed that with the trailer hitch thus stowed, the power loader may be used for loading and unloading freight without interference from the stowed hitch, no part of which will contact the ground when the power loader is fully lowered.

When the lifting arms 16 are in the fully raised position, the hitch may be put into use by first removing the retainer pin 60 allowing the ladder frame 35 and A frame 40 to swing clear for subsequent interconnection of their free ends. As is shown in H0. 8, the coupling of the two frames is'accomplished by inserting the tongue plate 39 of the ladder frame 35 between the slot-defining plates 53 and 54 on the rear end of the A frame 40. The forward end of the tongue plate 39 is formed with a semicircular notch 65 which abuts and embraces the shank of a stud 66 that is rigidly secured by welding 67 to span the slot defined between the plates 53 and 54 in which the tongue plate 39 is closely received. Adjacent their rear ends the plates 53 and 54 are formed with coaxially related holes 68 and 69 that register with a hole 70 formed through the tongue plate 39 when the tongue plate has been indexed in position by the stud 66. Thereafter, the retainer pin 60 is inserted to hold the ladder frame 35 and A frame 40 in coupled position with the forward end of the tongue 39 indexed against the stud 66 and so braced against angular movement about the pin 60 in response to lateral forces on the ball 24; if desired, a spring loaded button 71 may be provided in the lower-end portion of the retainer pin 60 to prevent axial displacement of the pin 60 and a flange 72 may be provided on the upper-end portion of the retainer pin to limit insertion of the pin through the alogned holes. I

With the hitch in operative position, a trailer 75 may now be connected for towing by the vehicle by means of the conventional ball socket provided in the forward end of the trailer ball 24 is positioned by the A frame 40 and ladder frame 35' within the plane of the rearmost extremity of the truck whereby the trailer is not unduly short coupled and the truck and trailer may be turned about corners of extremely short radius without interference therebetween.

While a presently preferred embodiment of the invention has been described by way of example, it is to be understood that the invention is not limited to the disclosed details of construction but only by the spirit andascope of the following claims. I

lclaim: 1. A collapsible trailer hitch for truck loaders comprising: a lifting arm frame adapted for mounting at the rear end-of a truck;

an opposed pair of hitchframe members, one of which is swingably mounted at a forward end thereof to a forward end of said frame, and the other of whichis swingably mounted at a rear end thereof to a rear end of said frame;

said pair of members being oppositely swingable towardsone another for overlapping their swingable ends in a stowed position thereof in which both said members are disposed approximately within the plane of said frame;

retainer means to releasably interconnect said frame and at least one of said members when said members are in thestowed position;

cooperating means on the swingable ends of said pair of members for rigidly interconnecting said swingable ends. when said pair of members are released from the stowed position to project downwardly from said frame whereby said frame and said pair of members define a rigid framework; and

a trailer coupling means mounted on one of said members that is arranged to be positioned at the apex of said pair of members when said members are rigidly interconnected by said cooperating means.

2. A trailer hitch as in claim-l in which:

saidcooperating means comprises a tongue affixed to the swingable end of said other member and a rigid means defining a slot that is rigidly affixed to the swingable end of said one member to matingly receive said tongue in a prevents withdrawal of said tongue from said slot-defining,

means and the other of which prevents relative angular movement of said tongue and slot-defining means about the axis of said one fastener means.

5. A trailer hitch as in claim 1 in which:

said lifting arm frame includes a spaced pair of linkage arms and a cross brace interconnecting rear ends of said pair of arms;

said one hitch frame member comprising an A frame having an apex defining said rear end of said one member;

said other hitch frame member comprising a substantially rectangular framework having a transversely disposed tongue at said swingable end of said other member and comprising a portion of said cooperating means for rigidly interconnecting said swingable ends of said pair of mem-. bers;

said rectangular framework being adapted to be generally disposed within the plane of said linkage arms when in said stowed position with a forwardly disposed end over lying said rear end of said one member to be supported thereon;

said retainer means comprising cooperating parts on said A frame and one of said linkage arms that are brought into coaxially alignable holes therethrough to receive a retainer pin therethrough. v

7. A trailer hitch as in claim 6 in which:

said trailer coupling means is situated on a rear end of said tongue; and

said tongue and said spaced pair of plates having cooperating portions at a position-offset from said retainer pin holes adapted to prevent relative angular movement of said tongue and said pair of plates when a retainer pin is mounted in said holes. 

